Raphaelo J. Fraberger

Zoologist

Vienna, Austria

The main field of my zoological research is the biology of non-Apis bees (superfamily Apoidea). Bees belong to the insect order "Hymenoptera", which also includes ants, wasps and others. With more than 14 000 species, Hymenoptera is the largest group of insects in central Europe.

Today´s entomologists expect between 20 000 - 30 000 different species of bees to exist. From central Europe, more than 700 bee species have been described. Non-Apis bees includes all "wild" bees since the honeybee Apis mellifera (fam. Apidae) is in human culture (there are only 11 Apis species in the world). According to Michener`s "Bees of the world" (John Hopkins Univ. Press, 2000), the bees of central Europe can be classified into the 6 following families:

Family Colletidae

Family Halictidae (sweat bees)

Family Andrenidae (sand bees)

Family Melittidae

Family Megachilidae

Family Apidae

Bees mostly live solitarely, i.e. each feamle builds a nest/nests of her own and provides the brood cells by herself. Larvae food obligatory is pollen that can be mixed with nectar. Only a few species (in central Europe only some melittid species) are specialised on collecting oil instead of pollen which they get from elaiophores - glands some plant species offer in their flowers. Food storage like the honey in honeybees only occurs in social species (in colonies) like in bumblebees (genus Bombus, Apidae). Also some of the European sweat bees (genera Halictus and Lasioglossum) have evolved sociality of different levels.

Non-Apis bees are relevant pollinators of crops like rape, alfalfa, tomatoes, fruits and others. Though poorly known, some of them are even more efficient than honeybees. Various species are specialised to certain plant species, nesting habitates or microclimatic conditions, no wonder that many bees are endangered today.

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Systropha & Biastes

There are two, rather rare speceis of spiral-horned bees in central-Europe, Systropha planidens and Systropha curvicornis (fam. Halictidae). Mating behaviour, reproductive biology and chemical communication were aims of my studies on Systropha.

The common name "spiral-horned bees" comes from the fact that the males of both species have "coiled" antennae: the five distal flagellomeres are reduced in size and usually folded up into a three-cornered spiral as the REM scans show below (left: idle position of the male antenna; right: detail; below: artificially expanded).

Spiral-horned bees are solitary and ground nesting. Females of both European species forage pollen exclusively on the lesser bindweed Convolvulus arvensis (Convolvulaceae), they are so-called oligolectous, i.e. pollen foraging is restricted to only a few host plant species. Another Convolvulus species (C. cantabrica) has been reported from the Mediterranean to serve as a pollen source. About 25 Systropha species have been described. They all come from the Old World and are expected to feed on Convolvulus resp. Convolvulaceae only. Very exceptional among bees is the manner how females carry the pollen to the nest: also the "back" of the female metasoma is used. The photo right below shows a pollen-loaded female in a bindweed flower.

Males (photo left below) patrol Convolvulus flowers where they establish territories and wait for the females. Copulations then take place in the flowers. The males also regularely sleep in the flowers where they get completely enclosed in the afternoon and are hidden for the rest of the day and during night.

Both Systropha species are parasited by Biastes brevicornis (fam. Apidae), a cuckoo bee. Cuckoo bees are cleptoparasites which neither build nests by themselves nor forage pollen for the larvae. The cuckoo females rather intrude nests of a host species and lay their eggs in provided cells. The cuckoo larva then lives from the pollen instead of the host larva which does not survive.

Like many other cuckoo bees, Biastes brevicornis is highly specialised on their host species (only Systropha bees) and has lost all hairs important for pollen transport. Males and females of cuckoo bees have no nests of their own and therefore typically sleep above the ground on plants, blades of grass etc. bitten with their mandibles only. The photo right below shows both sexes of Biastes brevicornis doing so with the black male on the right. The female has a red metasoma (photo left below).

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